Knife Steel
Composition, properties, and ratings of the most popular knife steels
What is Steel?
Steel is a unique material; strong and supple, yet hard and, at some point, brittle, of all the marvels that the human mind has conjured, steel, and its refinement, has remained at the cutting edge (heh) of technological development for at least three millennia.
At the most basic level, steel consists of an alloy of Iron with a certain amount of Carbon impurities, generally less than 2% (with exceptions), and a lower limit with no exact definition, although 0.02-.05% are commonly used numbers. Exactly how much Carbon, and what other elements (good or bad), determine the potential properties of the steel.
But those are only potential properties; how it is treated, from forging to quenching to tempering, is as important as the alloy itself. The atoms themselves form into crystals of different arrangements with different properties at different temperatures, and by changing temperature more or less quickly will result in different orientations.
The ideal result is a base material (called the solution) which is firm (hard) but ductile (tough), with harder pieces embedded in it (carbides or nitrides), like nuts in a muffin. The hard pieces grind away the material being cut, while the strong, ductile base acts like a spring to absorb some impact and prevent the hard pieces from breaking or being torn out.
In general, the relevant properties of a given steel are its hardness, toughness, wear resistance, corrosion resistance, and ease of sharpening. Hardness is resistance to compression (squeezing); toughness is resistance to fracture (breaking); wear resistance is ability to withstand abrasion (rubbing); and corrosion resistance and ease of sharpening are self-explanatory.
Note that these are not the only properties, and there tend to be trade-offs; wear resistance and hardness make sharpening more difficult, and are hard to combine with toughness; corrosion resistance comes from certain elements which have other effects; and hardness is not, exactly, the same thing as strength.
Steel Composition
First, let's talk about the different elements and the roles they play:
Iron (abbreviated Fe): The base material of steel, by itself it is a relatively soft, ductile metal. Its multiple crystal structures are the basis for the different properties of the steel, and its base carbides are, generally speaking, the softest. It is also susceptible to corrosion.
Carbon (C): The most important alloying element in steel, it serves two primary functions: It forms carbides with either Iron or other elements to provide the hard, cutting part of the steel, and within in the iron solution itself, it forms dislocations which harden the crystal structure. Too much carbon can become brittle, both from too many/large carbides (carbide volume) and from overhardening the iron base.
Manganese (Mn): A common natural impurity, the primary effect of Manganese is to alter the effects of heat treatment on steel by dramatically changing the rate at which transitions from one crystal structure to another occur, allowing for better hardness.
Chromium (Cr): Perhaps the single most powerful alloying element in steel after Carbon, Chromium has two primary functions: It forms carbides that are harder than Iron carbides, for better cutting ability and wear resistance, and at high concentrations (~12% and up) forms an oxide layer within the solution, inhibiting corrosion, creating Stainless steel, as well as improving toughness.
Vanadium (V): Next after Chromium, Vanadium also plays two key roles in high quality steel: It forms the hardest carbides found in knife steels, and, properly treated, it reduces carbide size, leading to improved strength and wear resistance. Large amounts require special forging techniques, such as Powder Metallurgy (PM), which increases cost.
Molybdenum (Mo): A complicated element, its role very much depends on which other elements are present and how the steel is treated. It can form carbides, either by itself or as compound carbides, and/or it can improve strength, hardness, and corrosion resistance in solution, but it works best by amplifying the effects of other elements, such as Vanadium. Large amounts require special forging.
Tungsten (W): Most commonly found in tool steels, its primary function is to improve high temperature performance of steel, but it also forms very hard carbides. Special forging for large amounts.
Silicon (Si): Another complicated element, Silicon has an effect on crystal structure transitions and formations, acting similarly to Manganese.
Nickel (Ni): Not the most common element in knife steels, it improves strength at the cost of hardness, and while at higher amounts can inhibit corrosion, it can only aid other elements for that purpose in blades or they will be far too soft.
Other elements: Some, like Sulfur (S) and Phosphorus (P), are in all steels, and others, like Nitrogen (N) and Niobium (Nb), are so rare that I will simply discuss them in context.
Putting It All Together
Let's start with some basic steels, such as AISI 1080, which has 0.8% Carbon, 0.6-0.9% Manganese, and some Sulfur and Phosphorus, which we largely ignore.
1080 can be considered "basic" because it is almost entirely Iron, and 0.8% Carbon is kind of a "magic" number in steel (called "Eutectoid"), a theoretical ideal that tends towards dramatically improved strength, but the lack of other alloying elements limits its toughness and wear resistance.
D2 has more Carbon, 1.5%, along with 12% Chromium and 1% each Vanadium and Molybdenum. Vanadium carbides are harder, providing better wear resistance, and the Chromium and Molybdenum (CroMoly) strengthens the alloy, but enough Carbon is left over to form Chromium carbides, leaving less Chromium in the solution, so the steel is not "fully" stainless, and the carbide volume is high, reducing toughness.
420, on the other hand, has less Carbon, 0.5%, but with 13% Chromium, it has better wear resistance than 1080 even with much lower carbide volume, still less than D2, but is tougher than either one, along with being "fully" stainless because most of the Chromium is left in the solution, if not saltwater resistant. It is an extremely tough but not very hard alloy.
These are the basic categories of knife steel: Carbon steel, with generally less than 5% alloying elements; Tool steel, with more than 5% alloy, but not enough Chromium (or other elements) to be stainless; and Stainless steel, with enough Chromium to be signficantly resistant to corrosion.
Advanced forging techniques, such as Powder Metallurgy (PM), improve some properties of steels, and can be either updated versions of old alloys or new alloys which can only be made with modern these techniques.
Ratings
Steels will be rated from 1-10 in the following categories: (T)oughness, (H)ardness, (W)ear Resistance, and (C)orrosion Resistance, and from cheap ($) to moderate ($$) to expensive ($$$).
(T)oughness is resistance to fracture; brittle steels require broader edges to avoid chipping.
(H)ardness is resistance to compression, and softer steels tend to roll edges if used on harder material.
(W)ear resistance is based on a abrasion resistance against silica-infused paper, which depends almost entirely upon carbide hardness and volume.
(C)orrosion resistance is based on resistance to, depending on the source, water, saline solution, saltwater, super-saturated saltwater, or various corrosive.
Note that I do not rate "Edge Retention" separately; each of the above properties has some effect on edge retention, and some are more important in some cases than others. Stainless steel is great for home kitchen knives, since you can just put it in the dishwasher and most people take awhile to use them enough to dull them, but professional chefs prefer carbon steels for most of their knives; since they use and sharpen them daily, ease of sharpening is important, corrosion resistance is not.
For convenience, I will be using a common formula of the element amount in percent, followed by its abbreviation, so 1080 will have (0.8C 0.8Mn) after it. The data set has been gleaned from multiple online and textual sources, and my own meta-analysis and personal testing data will be in a later post.
Suggestions will be noted below most alloys, to brands and items that I either have personal experience with, or their reputations are such that I have no hesitation in recommending them. This is my only profit from this project, so please help me make a little money from something you were going to buy, anyway, at no extra cost to you. Thanks!
Carbon Steels
1070 (0.7C 0.8Mn): Slightly lower Carbon than 1080, it is tougher with fewer carbides. T5 H3 W1 C0 $
Old Hickory 5-piece Knife Set: https://amzn.to/3sjXN9W
1080/1084 (0.8C 0.8Mn): As described above, something of an "ideal" steel, at least as far as traditional steels are concerned, it is not commonly seen in production knives in favor of the related 80CrV2. T4 H7 W1 C0 $
1095 (1C 0.4Mn): More Carbon gives better wear resistance at the cost of toughness, which lowers its hardenability. T3 H4 W2 C0 $
Ka-Bar Survival Knife: https://amzn.to/3srko4f
5160 (0.6C 0.9Mn 0.8Cr 0.3Si): A spring steel, it has even lower Carbon, but with Chromium carbides and oxide, Manganese, and Silicon, this is a very tough alloy. T10 H4 W2 C1 $
Buck 104 Compadre 4.5" Camp Knife: https://amzn.to/3u7yDM2
52100 (1C 0.3Mn 1.5Cr 0.3Si): High Carbon and some Chromium give decent edge retention, and it's quite tough. T7 H6 W2 C1 $
Cold Steel 9.5" Bowie Knife: https://amzn.to/3MxdtNT
80CrV2 (0.8C 0.5Mn 0.3Cr 0.2V 0.3Si): An updated 1080 steel, it tends to be a little softer but tougher, while retaining an ideal carbon balance. T7 H5 W1 C0 $
Demko Armiger 4" Tanto: https://amzn.to/3QIEYXl
Tool Steels
3V (0.8C 8Cr 3V 1.3Mo): Moving back the other way, this is a tougher moden steel with moderate carbide volume, but those carbides are Vanadium, and the CroMoly holds it together well. Very tough with good edge retention, this makes for excellent large blades. One minor drawback is that the carbides are so fine that it cannot be mirror finished. T9 H4 W4 C6 $$
Cold Steel Master Hunter 4.5" Hunting Knife: https://amzn.to/3tZhyUG
A2 (1C 1Mn 0.35Si 5Cr 2V 1Mo 0.3Ni): An older tool steel, quite hard with decent wear resistance. T4 H6 W2 C3 $$
Cold Steel 12" Bowie Knife: https://amzn.to/461zVWc
Cruwear (1.1C 8Cr 2.4V 1.6Mo 1.2W): A modern tungsten steel with balanced properties. T5 H7 W5 C6 $$$
Spyderco Stretch 2 XL 4" Backlock Pocket Knife: https://amzn.to/49oibav
D2 (1.5C 0.6Mn 0.3Si 12Cr 1V 1Mo 0.3Ni): An older tool steel, not stainless despite the Chromium, hard with high carbide volume. PM D2 is significantly tougher and more wear resistant. T3/5 (PM) H6 W4/5 C5 $$
Buck 120 General 7.375" Hunting Knife: https://amzn.to/3SolBnJ
M4 (1.4C 0.55Si 4Cr 4V 5Mo 5.5W): Another Tungsten steel with balanced properties, but expensive for knife purposes. T3 H7 W6 C4 $$$
Spyderco Bradley 2 3.66" Pocket Knife: https://amzn.to/49krHLR
Stainless Steels
14C28N (0.62C 14Cr 0.1N): A Nitrogen steel, Nitrogen acts similarly to Carbon, forming hard nitrides, and strengthening the steel, overall, but also adds corrosion resistance in relatively small amounts. T7 H4 W3 C8 $$
Civivi Spiny Dogfish Pocket Knife: https://amzn.to/40qMVUj
154CM (1.05C 14Cr 0.4V 4Mo): Developed from 440C, it replaces some Chromium with Molybdenum for good wear resistance, if only moderate strength. The PM version is tougher. T3/4 H3 W5 C7 $$
Kizer Drop Bear 3" Pocket Knife: https://amzn.to/3Sm6paG
420 (0.15C 13Cr): Also known as 13/0 in tableware, this is the original stainless steel. Its toughness and availabilty make it commonly used in many types of knives and cutlery, despite being relatively soft with low carbide volume. If you see a generic knife that just says, "Stainless Steel," it is probably this. T8 H1 W2 C9 $
Virginia Boys Chef Knife Set: https://amzn.to/3u1ZPvU
420HC (0.5C 13Cr 0.3V 0.6Mo): An update to 420 with more Carbon and some Vanadium and Molybdenum to retain toughness while improving hardness and wear resistance, this steel is popular with many premier knife makers. T9 H2 W3 C8 $$
Buck 110 3.75" Classic Pocket Knife: https://amzn.to/40nhKcz
440A (0.7C 1Mn 1Si 17Cr 0.75Mo): Another venerable stainless steel, it's high Chromium gives it solid corrosion resistance, if mediocre otherwise. T4 H2 W2 C8 $$
Boker Sierra Alpha 3.375" Pocket Knife: https://amzn.to/40nxJHy
440C (1.1C 1Mn 1Si 17Cr .75Mo): Just 440A with more Carbon, edge retention is increased at the cost of toughness. T2 H3 W4 C8 $$
Kyoku Kitchen Knife Set: https://amzn.to/3Stm7ku
8Cr13MoV (0.8C 1Mn 1Si 13Cr 0.1V 0.15Mo 0.2Ni): A modern Chinese steel based on the 440-series, it is tougher with similar edge retention, for less money. T6 H3 W3 C7 $
Yatoshi Kitchen Knife Set: https://amzn.to/3FKiteb
LC200N (0.3C 1Mn 1Mo 15Cr 0.5Ni 0.5N): Another Nitrogen steel, the combination with Nickel and plenty of Chromium gives this steel unparalleled corrosion resistance. T8 H3 W3 C10 $$$
Spyderco Waterway 4.44" Salt Knife: https://amzn.to/3Mrdfb9
Magnacut (1.15C 10.7Cr 4V 2Mo): The latest custom-designed steel, it is a quite hard and wear resistant steel with decent toughness, but it really shines in corrosion resistance despite relatively low Chromium from its precise ratio of Carbon to Vanadium. T4 H7 W5 C9 $$$
Kershaw Launch 3.5" Automatic Knife: https://amzn.to/49qBOPs
Nitro V (0.68C 0.7Mn 0.4Si 13Cr 0.1V 0.11N): Another Nitrogen steel with an unusual combination of properties. T5 H6 W3 C7 $$
Civivi 3" Pocket Knife: https://amzn.to/46Z3jhk
S30V (1.45C 14Cr 4V 2Mo): A modern custom-designed steel, but older than Magnacut. T3 H3 W5 C8 $$$
Kershaw Blur 3.4" Pocket Knife: https://amzn.to/3G5mF8N
S35VN (1.4C 14Cr 3V 2Mo 0.5Nb): Another modern steel, the Niobium acts similarly to and enhances the effects of Vanadium in forming small, hard carbides. T4 H4 W5 C8 $$$
Buck 102 Woodsman: https://amzn.to/40o3PTk
S45VN (1.48C 16Cr 3V 2Mo 0.5N 0.5Nb): So, what happens when you just throw everything at the wall and see what sticks? T3 H5 W5 C8 $$$
Spyderco Para Military 2 3.4" Pocket Knife: https://amzn.to/46c8GZa
S90V (2.3C 0.5Mn 0.5Si 14Cr 9V 1Mo 0.4W): Another Tungsten steel, the high Vanadium fraction makes this a very wear resistant alloy. T3 H4 W8 C8 $$$
Benchmade Osborne 940 3.4" Pocket Knife: https://amzn.to/40AkJyi
VG10 (1C 15Cr 0.2V 1Mo 1.5Co): A Japanese knife steel, the Cobalt addition is still something of a mystery, but overall it is a hard, fine-grained, but not especially tough steel. T3 H5 W4 C8 $$
Senken Chef's Knife Set: https://amzn.to/47iPVUP
X50CrMoV15 (0.55C 1Mn 1Si 15Cr 0.2V 0.8Mo): A German steel also known as 1.4116, it is commonly found in mid-range kitchen knives because it is forgiving of abuse and easy to maintain. T5 H1 W4 C8 $$
Zwilling Twin Signature German Kitchen Knife Set: https://amzn.to/46Z5TDY
"But Meta Modern Man, the steel I like didn't score very well!"
That's too bad; does it do what you need it to do? Do you know how to work with it, to sharpen it properly and use it appropriately? Knowing the properties of a given steel is more important than what those details are.
These ratings are not about, "This steel is better than that steel," but about, "This is what you need to know to get the most out of your knife."
Some of my favorite kitchen knives are 1070, why? Because they sharpen easily! It just takes a minute to put a razor edge on it, and it doesn't wear quickly cutting most food, anyway. Not stainless, but used and cleaned regularly, they patina, which is almost as good, as long as you keep using and caring for it.
420 is still popular over 100 years later, because it is well understood, the forging and treatment processes are very refined, and it is easy to get an inexpensive, reliable blade in a tough, stainless steel out of it. Some of my favorite outdoor knives are 420HC.
X50CrMoV15/1.4116 looks like a terrible steel, until you realize that it holds an edge well for food, is tough enough to put up with a little abuse, is easy to sharpen, and very corrosion resistant; this is perfect for someone who just wants a "good knife" but isn't necessarily the most responsible with it.
Don't get hung up on the details, the best knife steel is whatever the blade in your hand is made from.
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